1. Field of the Invention
Embodiments relate to an organic light emitting display and a method of manufacturing the same. More particularly, embodiments relate to an organic light emitting display capable of preventing electrical characteristics from deteriorating due to ultraviolet (UV) light and a method of manufacturing the same.
2. Description of the Related Art
An organic light emitting display is a next generation display having a self-emission characteristic and improved view angle, contrast, response speed, and power consumption than a liquid crystal display (LCD).
The organic light emitting display includes an organic light emitting diode (OLED) coupled between scan lines and data lines by a matrix method to construct a pixel. The OLED includes an anode electrode, a cathode electrode, and an organic emitting layer formed between the anode electrode and the cathode electrode. The organic emitting layer includes a hole transport layer, an organic light emitting layer, and an electron transport layer. When a predetermined voltage is applied to the anode electrode and the cathode electrode, holes injected through the anode electrode and electrons injected through the cathode electrode are recombined in the light emitting layer, which, in turn, emits light in response thereto.
The organic material in the OLED is vulnerable to hydrogen and/or oxygen. Further, the cathode electrode is easily oxidized by moisture, deteriorating electrical and light emitting characteristics. In order to prevent the electrical and light emitting characteristics from deteriorating, a can or cup shaped container made of a metal material or a sealing substrate made of glass or plastic is provided to face a substrate on which the OLED is formed. Then, sealing is performed using a sealant, e.g., an epoxy.
However, use of such a container or sealing substrate with an OLED to be used in a thin or flexible display is impractical. Therefore, in order to seal the thin or flexible display, a thin film encapsulation technology is provided.
As an example of the thin film encapsulation, a method of alternately laminating an inorganic layer and an organic layer to form an encapsulation layer is widely used, as this satisfies a water vapor transmission (WVTR) condition of about ˜10−6 g/m2/day required by the display. However, such formation includes providing an evaporation depositing liquid monomer and curing the evaporation deposited liquid monomer using UV light to form a polymer. As a result, the UV light is incident on the organic emitting layer. When UV light is incident on the organic emitting layer, thermal damage is generated to change the characteristics of the organic emitting layer and surface characteristics between the organic emitting layer and the cathode electrode, so that the electrical characteristics (I-V) of the OLED are positively shifted and/or a leakage current is generated, increasing power consumption and reducing the life of the OLED.
FIG. 1 illustrates a graph of a change in the electrical characteristics (I-V) of the OLED as a result of incident UV light. Curve A illustrates a measurement result before the UV light is incident and curve B illustrates a measurement result after the UV light is incident. When the electrical characteristic (I-V) changes, a higher voltage is required in order to maintain the brightness (cd).